this post was submitted on 09 Sep 2023
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Science Memes

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[–] [email protected] 70 points 1 year ago (6 children)

Explanation for mathematical illiterates?

[–] [email protected] 114 points 1 year ago (4 children)

A very wrong proof once showed that the sum of all positive integers (1 + 2 + 3 + 4...) was -1/12. In reality, the infinite sum has no solution, so this proof became something of a meme.

[–] [email protected] 26 points 1 year ago

Technically technically, in some number fields (not the natural numbers) it is correct, but since it doesn't apply to all number systems it's incorrect to say it's the answer without also specifying you're using a nonstandard number system.

As someone else said, it's used in quantum physics where a lot of fancy math is used in complex number fields.

[–] [email protected] 20 points 1 year ago

Ramanujan was a God tier memester

[–] [email protected] 5 points 1 year ago
[–] [email protected] 79 points 1 year ago* (last edited 1 year ago) (4 children)

https://en.wikipedia.org/wiki/1_%2B_2_%2B_3_%2B_4_%2B_⋯

TL;DR: in some interpretations, 1 + 2 + 3 + … equals to -1/12. This interpretation has actually found some uses in physics. In general, this is not widely accepted as it depends on a specialized meaning of the equals sign. It shouldn’t be used unless you really know what you’re doing.

[–] [email protected] 46 points 1 year ago (1 children)

I read that and am now more confused. Thanks!

[–] [email protected] 13 points 1 year ago

One of those cases where "first you learn the rules. Then you can learn how to break them."

[–] [email protected] 34 points 1 year ago (1 children)

Fr I didn't know what I was doing and tried it .. broke both of my legs and gave me a concussion.

Don't mess around with -1/12!

[–] [email protected] 1 points 1 year ago
[–] [email protected] 2 points 1 year ago (1 children)

I don't like the Ramanujan explanation at all because c - 4c doesn't equal the divergent series, since 4c is only supposed to subtract from every other number, so it has more terms at every single limit of n, and thus more terms at infinity. So c - 4c is just -3c, not a divergent series.

[–] [email protected] 6 points 1 year ago (1 children)

That's not how infinity works

[–] [email protected] 1 points 1 year ago (1 children)

Except it is. Infinities can have different sizes, and the size of an infinity needs to be taken into account when working with them.

Rama subtracted one infinity that is twice the size of another from it, so he subtracted twice as many numbers as his equation implies.

[–] [email protected] 15 points 1 year ago (1 children)

Infinities do have different sizes, yes. But not on that scale. Both of these are countably infinite sets.

Think about this: there are infinitely many primes. Obviously, not every number is prime. But you can still map primes 1:1 with the natural numbers. They're both the same size of infinity.

[–] [email protected] 0 points 1 year ago (1 children)

Not when you're adding them together.

c - 4c = -3 - 6 - 9 - 12...

In order to make c the same as the divergent series you have to subtract the series:

f = 0 + 4 + 0 + 8 ...

Which is not the same series as 4c.

[–] [email protected] 6 points 1 year ago (1 children)

Why not? How does that change the value?

[–] [email protected] 2 points 1 year ago (1 children)

It makes the series equal length. You'll notice this is discussed in the wikipedia article, and a bunch of bullshit handwaving has to be done to try and correct for it.

c - 4c = -3 - 6 - 9 - 12...

Simple as that, not some crap divergent series. Rama was a troll.

[–] [email protected] 6 points 1 year ago (2 children)

You're adding a bunch of zeroes. Zero is the additive identity. It doesn't change the value.

[–] [email protected] 1 points 1 year ago

To clarify you cannot add zeros to a non-convergent series, which the series c is.

In regular summation you are only allowed to add one zero to the start of a convergent series without changing it's value, since you know a convergent series has a specific answer.

But for non-convergent series you cannot do this mathematically in normal summation.

The value of a series is calculated by summing to n digits, and extrapolating. So c to 4 digits is 10, and to 5 digits is 15. 4c to 4 digits is 40, and to 5 digits is 60. But the series 4c with added zeroes at 4 digits is 12, and at 5 digits is still 12.

So 4c and 4c plus zeroes are not the same series. The only way to make 4c work in the posted equation is to use "super summation" which is a load of bull. Someone else posted a good video showing why this is the case.

[–] [email protected] 0 points 1 year ago

But it does change the length of the infinity.

once again:

c - 4c = -3 - 6 - 9 - 12...

That's it, that's the answer. Anything else is clearly false.

[–] [email protected] 2 points 1 year ago

This is how you make a black hole isn't it?

[–] [email protected] 13 points 1 year ago

Basically there's this meme that 1+2+3...= -1/12, which isn't true, but is related to something that is true.

[–] [email protected] 7 points 1 year ago

I'm not smart enough to explain it but it's a reference to Ramanujan Summation if you want to read about it yourself.

[–] [email protected] 6 points 1 year ago (1 children)
[–] [email protected] 9 points 1 year ago (2 children)

And here a presentation of why the above is wrong: https://www.youtube.com/watch?v=YuIIjLr6vUA

It's covered in the first 9 minutes of the video, followed by other fun math stuff related to it.

[–] [email protected] 5 points 1 year ago

For context, I knew it was wrong and was more providing a source of what made the meme blow up. Your follow up video is a great one.

[–] [email protected] 2 points 1 year ago

I love how excited this guy is. He can barely hold back and keeps giggling. It’s so endearing I had to watch the whole thing. Very interesting.

[–] [email protected] 3 points 1 year ago (2 children)

If you get one, will you ping me? Lol

[–] [email protected] 6 points 1 year ago (1 children)
[–] [email protected] 6 points 1 year ago

You're a good person. Thank you.

[–] [email protected] 2 points 1 year ago

Completely forgot about this for a few days and now I'm kinda drowning in explanations :))